Final answer:
The law of conservation of mass states that atoms are not created or destroyed in chemical reactions. The mass of the reactants equals the mass of the products, and the matter simply changes form.
Step-by-step explanation:
Law of Conservation of Matter
When matter undergoes chemical changes, the law of conservation of mass dictates that atoms are neither created nor destroyed. This applies to all chemical reactions, meaning that the collection of atoms present before the reaction is the same as after, despite the atoms being rearranged. According to this principle, chemical equations must balance, so the number of atoms of each element in the reactants equals the number of atoms in the products. Antoine Lavoisier, a French chemist, formulated this law in 1789, emphasizing that the mass remains constant throughout the chemical process. Even in burning, the mass of matter is conserved; it simply changes form, such as into gas, liquid, or solids.
In summary, chemical reactions involve the rearrangement of atoms, but the overall mass and number of atoms remain unchanged. This is a fundamental concept in stoichiometry, which deals with the measurement of elements within chemical reactions.